If it's helpful and only our experience but must say we're not 30ish..😉. Sailed Celebrity from Rome to Barcelona taking in Venice, etc in mid September into early October. Don't remember any children but must have been some considering law of averages. Cruisers ages I would say was 50ish to 80ish (minority in our experience). Our table companions, 8 of us, were approx: 25 - a honeymoon couple; couple in their 50's; another in 60s; and I remember 2 older ladies maybe 70s who were very quiet but seemed to enjoy the lively conversations. Weather was very nice, sunny and warm but Venice was rainy, cool and I wore 2 light golf jackets...didn't spoil our trip in a gondola or walk through Marks square. We were invited to sail away (one of the last from there) the next day and the weather was terrific...no sweaters. So it's changeable. Hope this helps and it wasn't too long an explanation. BTW...you can choose a table for 2 and then find friends around the martini bar, pool, or various activities. Lots of choices if you don't want to dine at a larger table and take pot luck...LOL.